Oil impregnated condenser



Nov. 14, 1933. c. H. CAINE OIL IMPREGNATED CONDENSER Filed Sept. 25,1929 I7ZU6 71/02:" C/zarlesflfa aw Wine 65 96" Patented Nov. 14, 1933OIL IMPREGNATED CONDENSER Charles H. Caine, Chicago, Ill., assignor toBrown & Caine (Chicago Division), of Tung- Sol Lamp Works, Ina, Chicago,Ill., a. corporation of Delaware Application September 23, 1929 SerialNo. 394,415

8 Claims.

. This invention relates in general to electrostatic condensers, morespecifically to oil impregnated condensers; and to means for clampingand sealing such condensers in a suitable container;

Condensers of the paper-foil type are extensively used as by-passcondensers in radio sets and in power packs therefor, for power factorcorrection, and for other similar uses. condensers are usually formed byrolling a pair of metallic hills with suitable insulation, usuallypaper, interposed between adjacent layers of the foil, and the assemblyso formed is impregnated with asuitable, dielectric compound and pressedinto the desired shape,

Thin metallic terminals are usually interposed between. the layers ofinsulation and in contact with the foils or plates of the condenser andbrought out to suitable terminal lugs to which the wires leading to theexternal circuit of the condensers are attached.

In encasings or housings of this type it has been the frequent practiceheretofore to place the compressed assembly in a suitable metallic can,and to wedge the unit in the can by cardboard or other suitable stripsplaced around it.

The assembly so constructed is finished by pourlug molten insulation,frequently an amorphous substance such as wax or an asphaltumderivative, into the can over and-around the con 3Q denser unit.

Condenser hlocks such as are commonly used in power packs for radio setsand the like, comprise a plurality of condensers encased in a suitablecontainer, with the terminals of the indi vidual condensers attached toa suitable terminal block upon which the external leads are led.

' These multi-unit bloclrs are frequently finished in the abovedescribed manner.

Condensers of this type are subject to the critig, cism that theimpregnation oi the condenser unit is not complete and whollymoisture-proof with the result that cracks frequently form in the wasimpregnation of the unit and moisture penetrates the condenser throughthese cracks causing aneventual break-down of these units.

Moreover, the cardboard wedges employed to press the condensers unit inthe can or housing prevent a free flow oi the molten insulation aroundthe unit inthat housing with the result that the condensers unit is notperfectly sealed in the can.

In my present invention I manufacture a condenser unit by rolling thefoils and insulation in the above manner and impregnate it in a suitableoil, preferably a mineral oil which is high- These not be deterioratedor decomposed by the oil 1y refined to lower its carbon content.Preferably the impregnation is preceded by a vacuum treatment whichwithdraws the moisture from thestructure, and the impregnation made withthe oil and under considerable pressure so as to ensure removal of alltraces of moisture and perfect penetration of the oil into theinsulation of the condenser.

In the preferred form of my invention I mount the unit so constructed ina clamping device which holds the plurality of units forming thecondenser block rigidly together and also spaces the block so formedaway from the walls of the can or casing in which it is'enclosed. As aresuit when the molten insulation material is poured into the can itflows freely around the condenser block and completely moisture-proofsand seals it. Since the unit is spaced away from the walls of thecontainer there is room for an appreciable thiclcnessof compound aroundit and the seal is thereby made perfectly and is lasting. Q

The oil with which the condenser units have been impregnated comes indirect contact with this outer sealing compound, which must therefore beamorphous and so constituted that it will if a perfect seal is to bemaintained. 1 have ioundthat a compound comprising a'combination meetsthese'requiremeuts. This compound does not emulsiiy with the oil, and isnotcrystab lized or decomposed in any way by contact with it. Douhtlessmany other compounds may also prove suitable for this purpose, and I amnot 4 therefore to be limited to the use of any particu lar compound.

in one embodiment of my invention the con denser is mounted with thecover of the can on the bottom side and the lead-out wires projected outthrough that cover. In other adaptations the housing is mounted uprightand the con doctors brought out through the top of it. These and manyother arrangements for mounting the housed condenser, are contemplatedand are within the teachings of my invention.

New, to acquaint those skilled in the art with Hm the teachings of myinvention reference is made to the drawing in which a preferredembodiment oi it is illustrated by way of example, and in which: v

Figure l is an elevational view of a completely m5 assembled condenser;

Figure 2 is a plan view or the condenser with the cover removed andshowing the terminal block;

Figure 3 is ,a cross sectional view taken along 1w the line 3--3 ofFigure 2 looking in the direction of the arrows;

Figure 4 is a cross sectional view taken along the line 44 of Figure 3looking in the direction of the arrows;

Figure 5 is a detailed view of one of the clamping members;

Figure 6 is a detailed view of the other clamping members.

The condenser illustrated is an electro-static condenser suitable foruse as a by-pass condenser in a power pack such aswould be used tofurnish current for a radio set or the like, and comprises the condenserunits 1, 2, 3, i and 5 which are encased in a single casing from whichelectrical connections 6, 7, 8 and 9 are led through the cable 10. Asshown, terminals 11, 12, 13, 14 and 15 of the separate condenser unitsare commoned and connected to the conductor 9 leading from the condenserblock.

The opposite terminals are indicated at 16, 17, 18, 19 and 20, withterminals 16 and 17 commoned and connected to the lead 6, terminal 18connected to the lead 7, and terminals 19 and 20 commoned and connectedto the lead 8. The particular manner of connecting up the variouscondensers forming the block is not of the essence of the presentinvention as any desired arrangement of the condensers in the block ispossible within the teachings of my invention.

The condensers as shown are each constructed of a plurality ofconvolutions of two metallic foils with paper insulation interposedbetween them, the dimensions of the foils and thickness of the paperbeing governed by the desired capac itance and insulation characteristicof the condenser unit.

The condensers so formed are grouped together as shown and held by aclamp which comprises two side pieces 21, and two end pieces 22. Theside pieces .21 are provided with inwardly depending grooves 23 and 24,best seen in Figures 4 and 5, which are brought into registration withhook-like flanges 25 and 26 formed in the edges of the end plates 22.The interaction of the plates so hooked together firmly binds thecondensers 1 to 5, inclusive, together and holds them securely as aunit.

The side plates 21 are also provided with upwardly depending feet 27 and28 upon which the terminal block 29 rests. Another projection 30.

extends upward from this end of the plate 21 and lies in the slot-31 inthe block 29, the extreme end portion 32 of this projection being bentover adjacent to the upper side of the terminal block to securely lockit in place on the assembly.

This terminal block 29, is thus rigidly supported in the manner of abridge over the end of the condensers, and serves as rigid terminal forthe contacting strips 11, 12, 13, 14, 15, 16, 1'7, 18, 19, 20 of thecondensers. These strips are preferably made of very thin metal andsince they are held in contact with the plates of their respectivecondensers only by friction, it is imperative that they be rigidlysupported so that strains placed on them by the wires of the connectingcable, will not dislodge them from the assembly.

In the manufacturing of condensers of this type, the clamping of theunits and terminal block in the above manner proves advantageous for thereason that the rigidity oi. the assembly permits soldering theterminals together before the units are impregnated. This insures a goodjoint since the contacting strips 11-20 inclusive are clean at thistimeand can be easily fluxed and readily soldered. The rigid bridge-liketerminal block 29 supports the thin terminals'to facilitate solderingthem, and also prevents the flow of soldering flux along the terminalinto the condenser assembly.

After the terminals have, been soldered together the condensers,clamping members and terminal strip are all immersed in an impregnatving bath. Preferably the impregnation of the condensers is accomplishedby the usual vacuum process, the details of which are not of the essenceof the present invention and are so familiar to those skilled in theart'that a description of them is not necessary herein.

The material used to impregnate these condensers may be varied withinthe teachings of my invention. For certain purposes I have found thathighly refined petrolatum, which is semi-solid at ordinary roomtemperatures, is a very satisfactory impregnating medium. In otherinstances I have found that vegetable oils of similar viscosity ,atordinary temperatures are preferable. In certain types of condensers Iuse a mixture of vegetable and mineral oils to secure the desired characteristics. The choice of the particular impregnating medium will, ofcourse, depend upon the desired characteristics of the finishedcondensers. Ordinary parafiinwax may also be used when desired, withinthe teachings of my invention.

In practice I have found it advantageous to place a large globule orlump of solder on the terminals when they are soldered together, thatsupply being subsequently used toattach the terminal wires from thecable 10 to the terminal, that operation taking place in the finalassembly, and after the units have been impregnated. Even though theterminals are then covered with the impregnating compound, a goodelectrical joint can be made between the wire and terminal since thesolder which makes this joint is already in clean contact with theterminal. The wires are tinned previously and the joint can be quicklyand cheaply made by laying the wire on the globule of solder and heatingit until the solder melts.

The lower edge of the plate 21 is provided with the clamping member 33which is bent inward before the condenser has been assembled to preventthe condensers from slipping downward through the clamp, as will best beseen in Figure 3.

As shown the condenser 5 is smaller than the other units in the block,and it is therefore necessary to insert a spacer 15 between thecondensers 2 and 3 together with the condenser 5 to fill up the voidthat would otherwise be left between these condensers.

This filler 15 may be cardboard or any other preferred material.

In condenser blocks such as are used in power packs, the high voltageencountered makes it desirable to insulate the individual condenser insuch a manner that there is no likelihood of a flashover to ground.

To this end I have provided the insulating member 21 which surrounds thefive condensers shown and prevent them from coming into electricalcontact with the metallic clamping plates 21 and 22. This insulation 21'may be fiber, heavy paper, or any other preferred sheet material. Alsothe condenser 5 is insulated from the condensers 2 and 3 by a sheetofinsulation 2' to increase the insulation resistance between those units,and to prevent creasing of those units by the pressure exerted on themby the unit 5.

To protect the condenser blocks so formed from v moisture I haveprovided the can 39 which is rectangular in shape and constructed ofsuitable" sheet metal such as tin orbrass; this can 39 being of suchdimensions that the condensers held together by clamps 21 and 22 freelyslide into it. As will be best seen in Figure 3-, the condenser sodisposed in the can is supported up or above the bottom thereof by thefeet 34 and 35, and spaced away from the side of the can by the cars 38which.

are formed as projections in the surface'of the end plate 22,.

Similar projections 36 and 37 formed in the surface of the side plate 21space the condenser block away from the side walls of the can in asimilar manner.

' Preferably the can is of such a height thatit extends well above theupper surface of the terminal block 29, and in one preferred embodimentof my invention-it is provided with a.metallic cover 42 containing thebushing 41 and the screws Hand 45, the latter being projected throughopenings in the cover and-securely soldered in these openings as shownat 47.

Thesescrewsgil and 45 facilitate mounting the block on a suitablesupport with the cover on the bottom side of it.

The condenser unit is assembled by placing the condenser block in thecan, attaching the electrical conductors of cable 10 to theproperbinding posts, and then filling the can with an insulationmaterial whibh may be, a waxy compound, an asphaltum derivative, or anyother preferred amorphous material. Since the condenser block issupported up off of the bottom of the can, this insulation flows beneaththe block and perfectly seals that end of the block. Also since theclamping plates 2i and 22 are spaced away from the walls of the can, theinsulation flows freely around it forming a body of appreciablethickness which seals of the block. d

In the preferred embodiment of my. invention, suflicient molteninsulation preferably as phaltum or a mixture of asphaltum and wax ispoured into thecan to completely fill the space above the terminal blockand surrounding the end of the cable 10, and the cover 42 is placed intoplace while this insulation is still hot causing it to adhere totheinside surface of they cover which is then soldered into place in theusual manner. This completely seals the con-',

denser block in the can and guards against the possibility of moistureentering the condensers by creeping along the cable. The cable 10 isitself moisture-proofed by impregnation in suittion by disclosingapreferred embodiment of it,

I have done so by way of example only as there are many nodificationsand adaptations which can be made by one skilled in the art withoutdeparting from the teachings of the invention.

the side surfaces While I have chosen'to illustrate my inven- Havingthus complied with the statutes and shown and described the preferredembodiment of my invention, what I consider new and desire to haveprotected by Letters Patent-is pointed out in the appended claims.

What is claimed'is:

1. In combination, a container, a plurality o condenser units, a clampforming a closed loop about said units, said clamp comprising pairs ofsideparts having hooked engagement for closing the loop. about thecondenser units, said side parts having integral extensions projectingbelow the condenser units for spacing said units from the bottom of thecontainer, and integral tabs struck out from opposite sides of the sideparts for spacing the condenser units from the sides of the container.

2. An electrical condenser unit comprising a plurality of separatecondensers, a terminal block on which the terminals of said separatecondensers are grouped and connected to a cable leading outward from theunit, a metallic clamp for holding said condensers together'and alsoattaching the. terminal block thereto, spacing means on said clamp, acan for housing said unit, the walls of the can being-spaced away fromsaid unit by said spacing means, and amoisture-proofing compoundsurrounding said condensers and terminal block.

3. An electrical condenser unit comprising a plurality. of separatecondensers, a clamp for holding said condensers together, terminals onsaid condensers, a terminal block formed of an insulating material andsupported on said clamp adjacent to said condensers, said block havingslots in which said terminals are supported, a can in which saidcondenser is housed, and means on said clamp for supporting the'con-,densers in said can and for spacing them away from the walls thereof.

4. A clamp for holding condensers together comprising four rectangularsheet metal mem-. bers two,of which have grooves formed on their sidesand a-pair of feet and a clamping member formed in their ends, the othertwo members densers and clamped in a suitable housing and others of saidfeet supporting a terminalblock on the condensers, said clamping'membershold-. ing said condensers and terminal block in place, anda pluralityof ears formed in said four members for spacing said condenser in thehousing.

' 5. A bracket for compressing the units of a condenser block and forholding them within a protective casing comprising four metallic platesfitted on the sides and ends of the block, said end plates beingchanneled and said sideplates being fitted within said channels tocompress the block, feet projecting from one edge of said end plates tosupport the block, retaining lips pro-.- jecting from one edge of saidside plates to sup-. port the block in the bracket, and a plurality ofspacers projecting from-the surfaces of said plates to space the blockand bracket.

6. In a condenser block, the combination'with a plurality of paper-foilcondenser units having terminals connected together and connected toleads extending outward, through the can in which the condensers arehoused, of a sheet of insulation wrapped around said condensers ametallic clamp surrounding the condensers and insulation, said clampcomprising four plates joined together at their adjacent edgesby'fianges, and

condenser units for clamping said units together, and a container, saidclamp having opposite side portions provided with opposite projectionsengageable with the sides of the container to space the condenser unitsaway from the side walls of the container, the internal width of thecontainer being substantially equal to the distance from the tip of oneof said projections to the tip of the opposite projection whereby theopposite pro-- jections fit against the opposite side walls and positionthe condenser substantially centrally therebetween.

CHAS. H. CAINE.

